1. Field of the Invention
This invention relates to a coating method which develops an electrostatic latent image with a non-magnetic developer.
2. Description of the Prior Art
In the prior art, various devices have been proposed and practically used as the dry system one-component developing device. However, in any of these developing systems, it is very difficult to form a thin layer of a dry system one-component developer and therefore developing devices have been constituted so as to form relatively thick layers. Whereas, at the present time, when improvement of sharpness, resolution, etc. is sought after, development of a method for thin layer formation with the dry system one-component developer is essentially required.
As the method for forming a thin layer of a dry system one-component developer known in the art, the method as disclosed in Japanese Laid-open Patent Application No. 43037/1979 is proposed and practically applied. However, this concerned thin layer formation of a magnetic developer. A magnetic toner must contain a magnetic material added internally therein in order to have magnetic property. This, however, involves problems such as bad fixing characteristic when heat fixing the developed image transferred to a transfer paper or bad color during color reproduction due to internal addition of a magnetic material to the developer itself.
For overcoming these drawbacks, there have been proposed the method in which soft fur such as fur of a beaver is formed into a cylindrical brush and the developer is attached thereon for coating, and the method in which the developer is applied to a developing roller of which surface is made of a fiber such as velvet by means of a doctor blade, etc. However, when an elastic blade is used as the doctor blade for the above fiber brush, although the amount of the developer can be regulated, no even coating can be effected. Further, since triboelectric charges cannot be imparted to the developer existing between the fibers of the brush by only friction of the fiber brush on the developing roller, there has been the problem that ghost or other inconveniences will readily be generated. Besides, presence of non-magnetic developer made it difficult to prevent leak of the developer from the device.